Aerosol treatment with MNEI suppresses bacterial proliferation in a model of chronic Pseudomonas aeruginosa lung infection.

Neutrophil elastase is present at high levels in airway fluid of patients with cystic fibrosis (CF), and is responsible for considerable inflammatory damage. Human monocyte/neutrophil elastase inhibitor (MNEI), a 42-kDa serpin protein, is an effective inhibitor of neutrophil elastase, cathepsin G, and proteinase-3, related proteases released from inflammatory neutrophils. We hypothesized that recombinant MNEI would reduce inflammatory damage and enhance bacterial clearance from the lung in an animal model of chronic Pseudomonas aeruginosa infection. In vitro studies showed that MNEI causes dose-dependent inhibition of the activity of rat neutrophil elastase. Recombinant MNEI was administered daily by aerosolization to rats previously inoculated with agar beads containing P. aeruginosa to initiate chronic infection. Administered MNEI was partially recovered in lavage fluid of treated rats as a 66-kDa complex with protease indicative of in vivo inhibition of elastase or a related protease. Aerosol treatment with MNEI significantly decreased the extent of inflammatory injury, quantified as the histopathology score. MNEI, which had no bactericidal effect on P. aeruginosa in vitro, significantly enhanced clearance of bacteria from infected rat lungs. The reduction of histopathology scores and enhancement of bacterial killing were evident 6 hr after a single aerosol treatment with MNEI. These findings indicate an important function of MNEI in protecting innate antimicrobial defense. Similar results were previously obtained for aerosolized prolastin (alpha1-antitrypsin), indicating that enhanced bacterial clearance by MNEI is due to inhibition of neutrophil protease. These findings demonstrate the value of this nonantibiotic protease inhibitor as an adjunct for the treatment and prevention of the infection component of CF lung disease.

Wiskott-Aldrich syndrome in a female.

Wiskott-Aldrich syndrome (WAS) is an X-linked disease characterized by thrombocytopenia, eczema, and various degrees of immune deficiency. Carriers of mutated WASP have nonrandom X chromosome inactivation in their blood cells and are disease-free. We report data on a 14-month-old girl with a history of WAS in her family who presented with thrombocytopenia, small platelets, and immunologic dysfunction. Sequencing of the WASP gene showed that the patient was heterozygous for the splice site mutation previously found in one of her relatives with WAS. Sequencing of all WASP exons revealed no other mutation. Levels of WASP in blood mononuclear cells were 60% of normal. Flow cytometry after intracellular staining of peripheral blood mononuclear cells with WASP monoclonal antibody revealed both WASP(bright) and WASP(dim) populations. X chromosome inactivation in the patient's blood cells was found to be random, demonstrating that both maternal and paternal active X chromosomes are present. These findings indicate that the female patient has a defect in the mechanisms that lead in disease-free WAS carriers to preferential survival/proliferation of cells bearing the active wild-type X chromosome. Whereas the patient's lymphocytes are skewed toward WASP(bright) cells, about 65% of her monocytes and the majority of her B cells (CD19(+)) are WASP(dim). Her naive T cells (CD3(+)CD45RA(+)) include WASP(bright) and WASP(dim) populations, but her memory T cells (CD3(+)CD45RA(-)) are all WASP(bright). After activation in vitro of T cells, all cells exhibited CD3(+)CD45RA(-) phenotype and most were WASP(bright) with active paternal (wild-type) X chromosome, suggesting selection against the mutated WASP allele during terminal T-cell maturation/differentiation.